Notes on Science for HDNB-Y7 Mr. Hannes Xiao, MSc

FORCES AND THEIR EFFECTSLearning Objectives

（KS3 UK）(1) Understanding that forces are usually pushes and pulls between two objects(2) Knowing that forces are measured in newtons(3) Knowing that forces can make objects speed up, slow down, change direction or change shape

（ZHONGKAO）(1)能描述力的概念，知道物体间力的作用是相互的；(2)能说出力的作用效果；(3)会正确使用弹簧测力计测量力，知道力的单位。Classroom Activities1. Think up an example of how forces are used:

2. Name that force!

1.______ 2. ______ 3. ______ 4. ______ 5. ______

3. Definition: Forces are pushes or pulls that occur when two objects interact.

力是物体对物体的作用.

4. Leaning against each other

Every force has a _________ (施力物体) and a __________(受力物体). 有施力物

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Notes on Science for HDNB-Y7 Mr. Hannes Xiao, MSc

体必定有受力物体.Forces happen when two objects interact with each other.

A force arrow shows the direction of a force.

A girl is pulling a sack. The source object of the force acting on the sack is _________, the target object of this force is _________.

5. Objects don’t need to touch to interact. The gravitational pull between planets, forces between magnets are all non-contact forces.

6. Activity: 使弹簧、橡皮泥、皮筋发生形变；用磁铁改变钢珠运动状态.Effects of forces: forces can make objects speed up, slow down, change direction, turn or change shape.

力的作用效果是：（1）——————————————————— （2）———————————————————

7. Measuring ForceWe use an instrument called a __________ to measure a force. Another name for this

is a ___________. We measure forces in _________. 请在下图标注各部件英文名称.

8. Launch a balloon rocket:Preparation

• Tie one end of the string to a chair, handle or other steady object.

• Thread the string through the plastic straw.

• Making sure the string is taut (绷紧), tie it to another

chair or handle at least 10 feet (= _____ m ) away, and making sure the area around the string is clear.Procedure

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Notes on Science for HDNB-Y7 Mr. Hannes Xiao, MSc

• Blow up your balloon and pinch(捏住 ) the opening with your fingers to

keep the air inside. (Don't tie it off.)• While you are pinching the end of the balloon, secure it onto the bottom of

the plastic straw with a few pieces of tape.• Pull the full balloon with the straw to one end of the string, so that its

opening faces in the opposite direction from the clear line of string ahead of the balloon.

• Let go of the balloon, then release its opening.

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